These studies are designed to determine the role of autonomic activity in behavioral effects of stimulant drugs. The objectives of this project are to investigate relationships among differences in personality, sensory thresholds, and autonomic nervous system (ANS) activity in normal humans and to study racial differences in ANS activity. Bilateral skin conductance and heart rate have been recorded in two sessions in which constant and variable intensity tones and lights are presented and auditory and two flash thresholds determined by methods which permit signal detection analyses. Several standardized personality tests were also given. These include scales of sensation seeking, extraversion, neuroticism, psychoticism, field dependence and anxiety. In addition comprehensive measures of lateral dominance have been given as well as a measure of "torque" (clockwise drawing of circles) which is thought to reflect a neurointegrative deficit and be related to risk for future psychopathology. The procedures allow determination of the effects of stimulus intensity and heteromodal stimulation on ANS activity. A procedure for manipulating ANS arousal experimentally with minimal distracting effects--a change in posture from supine to standing--is being used to assess the effects of arousal on performance and the effects of personality variables on this relationship. This project allows testing of several theoretical methods of the relationships of ANS activity, sensory sensitivity, and personality, some of which have implications for the etiology of psychopathology. Tests of the relationships between laterality in skin conductance variables and behavioral laterality will also be done to see if inferences about lateralized brain function can be made from such variables.